A series of experiments are proposed to investigate the functions of the lateral suprasylvian visual cortex (LS, or Clare-Bishop area) in the cat, and its interrelations with other portions of the visual system. Several of the experiments will study the specific properties of the LS area inputs. Visual receptive field characteristics of single neurons in the lateral posterior and posterior nuclei of the thalamus will be investigated. Those cells which project directly to the LS cortex will be identified electrophysiologically and their conduction velocities determined. Similar information will be obtained for cells in striate cortex which project to the LS cortex. Other experiments will investigate the contribution of each input pathway for the receptive field characteristics of cells in the LS cortex. The effects of removing the superior colliculus or the thalamic-LS cortex projections on the receptive field properties of LS cortex cells will be studied. These results will be compared with previous results from this laboratory using normal cats and cats with cortical areas 17, 18, and/or 19 removed. The effects of visual deprivation during development on the receptive field properties of cells in the LS cortex will be investigated. Additional experiments will be conducted to determine the extent to which any abnormalities observed are a result of inputs from visual cortex or are intrinsic to the LS cortex and its thalamic projections. Behavioral functions of the LS cortex will be investigated. The effects of LS cortex damage on performace of a variety of behavioral tasks designed to test visual attention and visual discrimination behaviors will be assessed. BIBLIOGRAPHIC REFERENCES: Hickey, T.L., Spear, P.D. and Kratz, K.E. Quantitative studies of cell size in the cat's dorsal lateral geniculate nucleus following visual deprivation. Journal of Comparative Neurology, 1977, 172, 265-281. Spear, P.D., Smith, D.C., and Williams, L.L. Visual receptive field properties of single neurons in the cat's ventral lateral geniculate nucleus. Journal of Neurophysiology, 1977, in press.